Download The Connecticut River Valley

The Connecticut River Valley
Scenario: The Connecticut River is easily navigable from Long Island Sound into
Massachusetts. A trip up the length of the Connecticut River reveals the
evidence in the rock layers of each of the events in its history. Those who cannot
travel by boat can take a virtual tour via the planetarium dome to visit geologically
interesting sites.
Information below is from Richard D. Little Professor of Geology, Greenfield
Community College, Greenfield, MA:
http://www.bio.umass.edu/biology/conn.river/crvgeology.html
http://www.earthview.pair.com/ctriver.html
The Connecticut River is the largest in New England. It begins near the Canadian
border and flows more than four hundred miles between Vermont and New
Hampshire, and through Massachusetts and Connecticut to Long Island Sound.
The Valley began to form in the Paleozoic Era, about 600 million years ago,
when most of the land that would become New England was under water.
Tectonic activity pushed layers of sedimentary rock into metamorphic mountains
and ridges. The upwelling of magma made igneous flows along some of the
slopes.
During the Mesozoic Era, continental shifts created the rift that is the Atlantic
Ocean and a smaller one that became the river valley. By 65 million years ago,
earthquakes had titled the floor of the valley so that it pointed down towards the
Atlantic. Silt and sediment flowed into the valley and built up the floor as the
higher mountains were eroded. During the Cenozoic Era, glaciers eroded part of
the valley and deposited land along eastern Massachusetts, Connecticut, and
New York. A temporary lake, Lake Hitchcock, 16,000 years ago deposited layers
of clay along portions of the river path. Once the lake retreats, the river
reestablishes its course. Some portions follow the original valley floor while
others take new paths over boulders and cliffs. The river ends in Long Island
Sound as an extensive tidal basin.
What I know…
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I’ve learned through previous museum exhibits that Connecticut is made
of at least four different geologic pieces that were added at different times
as the continents shifted. Geologists have found matching rock formations
in South America and Africa that indicate where the continents were once
connected.
The floor of the Connecticut River Valley is made of soft clays and other
sedimentary rock. Even though large fossils have not been found,
dinosaur footprints and fossil fish are common in central Connecticut.
There is fossil footprint site about ten miles from here called Dinosaur
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State Park. Our museum has pieces of flat stone with footprints in it known
as Eubrontes, the official state fossil.
Where ever highways have been blasted through the central part of the
state, different colored layers of rock can be seen along the sides. Even
though there is no water there, there are brownish cliffs in East Haven
through which highway tunnels have been carved.
The lower portion of the Connecticut River is wide and flat and the shore
slopes gently to the water. In the spring, snowmelt makes the lowest
portion, in Middletown and East Hartford CT, overflow its banks. I’ve seen
the water cover ¼ mile on either side.
Where the river joins Long Island Sound, there are extensive marshes,
sandbars, and mudflats. I’ve taken a boat to the shore to watch where
swallows gather in the spring and fall on their migrations.
The upper part of the Connecticut River separates New Hampshire and
Vermont. It flows through a channel with rockier, steeper sides here than
in the lower half. I’ve driven past areas where the water is faster and flows
over boulders making whitewater and small waterfalls.
Deposits of sediment in northern Connecticut and southwestern
Massachusetts make for good growing conditions along this part of the
valley. While much of Connecticut is famous for having rocky soil, this land
is perfect for corn and tobacco. There are more vegetable farms along the
river than in other parts of the state.
Portland, CT is famous for its brownstone. Quarries were mined for
building materials for hundreds of years. Today, some of those older
quarries are flooded by aquifers and used for recreation.
What I don’t know…
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Where are the geological boundaries of the rock types? Where does one
area meet another?
Why are there so few dinosaur bones found even though there are
footprints and shells?
There are places where the river forms waterfalls and drops several feet.
What are the geologic conditions at these places?
Where are the best places to find examples of sedimentary, igneous, and
metamorphic rock?
What conditions make it difficult to build a city at the mouth of the
Connecticut River?
Why are semi-precious stones, like garnets, found in Central Connecticut
near the river?
Snow melts into the river from the northern Appalachians. Where does the
snowmelt originate?
The river originates in the Fourth Connecticut Lake. Where does the water
come from?
Event = The Connecticut River Valley is formed over millions of years.
Shifting tectonic plates (L) push up the land (L) under the ancient sea (H) in what
will become New England (E). L > (L + H) > E
The moving plates (L) force magma to the surface (E). L > E
The plates move farther apart (L) and form rift valleys which fill with water (H).
One will become the Connecticut River and the other the Atlantic Ocean (E).
L>H>E
Earthquakes (L) tilt the river valley (E) towards the coast. L > E
Water (H) pushes silt and sediment (L) into the valley (E). H > L > E
A glacier (H) scrapes the valley (E) and pushes the sediment (L) into Long Island
Sound (H). H > E > L > H > E
As the glacial lake (H) retreats, it builds layers of sediment (L) and lays them in
the valley (E). H > L > E
The river (H) finds its course (L) to the ocean (H) through the Connecticut River
Valley (E). H > L > H > E
Questions to think about when building the Virtual Field Trip:
1. Which are the locations to be included on a virtual tour of the Connecticut
River Valley? Since students will mostly be concerned with Connecticut,
how much should I include of points farther north?
2. The tour starts in Long Island Sound and travels up to Canada. How far
away from the current river banks should the project encompass?
3. How can I balance the need to meet state science standards with making
the project interesting for students/visitors?
4. From a technical angle, where can I get photos and video that will look
best in the planetarium while still telling the story? Can I buy other
people’s work, or do I need to take fresh pictures on my own?
5. To add interest to the work, should I include information about business
and industry developed because of the river and its geology?
6. Where do fossils and dinosaurs fit?